U.S. patent application number 10/352257 was filed with the patent office on 2003-09-18 for apparatus for cyclical deposition of thin films.
This patent application is currently assigned to APPLIED MATERIALS, INC.. Invention is credited to Al-Shaikh, Ayad A., Gelatos, Avgerinos V., Glenn, Walter Benjamin, Khan, Ahmad A., Mak, Alfred W., Thakur, Randhir P.S., Umotoy, Salvador P., Xi, Ming.
Application Number | 20030172872 10/352257 |
Document ID | / |
Family ID | 27663006 |
Filed Date | 2003-09-18 |
United States Patent
Application |
20030172872 |
Kind Code |
A1 |
Thakur, Randhir P.S. ; et
al. |
September 18, 2003 |
Apparatus for cyclical deposition of thin films
Abstract
An apparatus for cyclical depositing of thin films on
semiconductor substrates, comprising a process chamber having a gas
distribution system with separate paths for process gases and an
exhaust system synchronized with operation of valves dosing the
process gases into a reaction region of the chamber.
Inventors: |
Thakur, Randhir P.S.; (San
Jose, CA) ; Mak, Alfred W.; (Union City, CA) ;
Xi, Ming; (Palo Alto, CA) ; Glenn, Walter
Benjamin; (Pacifica, CA) ; Khan, Ahmad A.;
(Milpitas, CA) ; Al-Shaikh, Ayad A.; (Santa Clara,
CA) ; Gelatos, Avgerinos V.; (Redwood City, CA)
; Umotoy, Salvador P.; (Antioch, CA) |
Correspondence
Address: |
Patent Counsel
Applied Materials, Inc.
P. O. Box 450A
Santa Clara
CA
95052
US
|
Assignee: |
APPLIED MATERIALS, INC.
|
Family ID: |
27663006 |
Appl. No.: |
10/352257 |
Filed: |
January 27, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60351561 |
Jan 25, 2002 |
|
|
|
Current U.S.
Class: |
118/715 ;
118/723E |
Current CPC
Class: |
C23C 16/45536 20130101;
H01J 37/32009 20130101; C23C 16/4412 20130101; H01J 37/32091
20130101; H01L 21/6719 20130101; C23C 16/45582 20130101; C23C
16/45544 20130101; H01J 37/3244 20130101; H01J 37/32834 20130101;
C23C 16/45565 20130101; C23C 16/452 20130101 |
Class at
Publication: |
118/715 ;
118/723.00E |
International
Class: |
C23C 016/00 |
Claims
What is claimed is:
1. An apparatus for cyclical deposition of thin films on a
semiconductor substrate, comprising: a process chamber comprising a
gas distribution system having paths to separate process gases,
said paths extending from an intake port for a process gas to a
reaction region of the chamber; an exhaust system synchronized with
operation of valves dosing the process gases into the reaction
region to separate exhausted gases.
2. The apparatus of claim 1 wherein said paths are formed in a lid
and in a showerhead of the process chamber.
3. The apparatus of claim 2 wherein the showerhead comprises at
least one centrally located opening fluidly coupled to a first
path.
4. The apparatus of claim 3 wherein the showerhead further
comprises a dispersion plate to disperse into the reaction region
the process gas flowing through the at least one centrally located
opening.
5. The apparatus of claim 2 wherein the showerhead further
comprises a plurality of openings fluidly coupled to a second path
and the reaction region.
6. The apparatus of claim 5 wherein the at least one opening
further comprises a gas nozzle coupled to the opening.
7. The apparatus of claim 2 wherein said paths are further formed
around a substrate support in a body of the process chamber.
8. The apparatus of claim 7 wherein said paths are each a
circumferential channel coupled to a plurality of gas nozzles for
dispersing a gas into the reaction region.
9. The apparatus of claim 8 wherein the gas nozzles coupled to
different circumferential channels are disposed in an alternating
order.
10. The apparatus of claim 2 wherein the showerhead further
comprises a plurality of fluidly coupled gas channels, said
channels are fluidly coupled to a first path and the reaction
region.
11. The apparatus of claim 10 wherein the showerhead further
comprises a plurality of openings fluidly coupled to a second path
and the reaction region.
12. The apparatus of claim 11 wherein the showerhead further
comprises a blocking plate disposed in the lid and defining a
volume between the blocking plate and showerhead, said volume is
fluidly coupled to one of the intake ports.
13. The apparatus of claim 12 wherein the showerhead and the
blocking plate are electrically isolated from one another, the lid,
and the body of the process chamber.
14. The apparatus of claim 13 wherein the showerhead is
electrically biased using a source of a direct current or
radio-frequency power to form a plasma in the reaction region of
the chamber.
15. The apparatus of claim 13 wherein the blocking plate is
electrically biased using a source of a direct current or
radio-frequency power to form a plasma in the volume between the
blocking plate and showerhead.
16. The apparatus of claim 12 wherein the showerhead and blocking
plate are electrically biased using at least one source of direct
current or radio-frequency power to form a plasma and an electrical
gradient in the volume between the blocking plate and
showerhead.
17. The apparatus of claim 1 wherein the process chamber further
comprises an exhaust channel fluidly coupled to the reaction
region.
18. The apparatus of claim 17 wherein the exhaust channel comprises
at least one outlet port, each said outlet port is fluidly coupled
to an intake port of the exhaust system.
19. The apparatus of claim 17 wherein the exhaust channel is formed
between a liner disposed around the substrate support and the body
of the process chamber.
20. The apparatus of claim 1 wherein the exhaust system comprises
at least one intake port, each said intake port is fluidly coupled
to a controlled shut-off valve.
21. The apparatus of claim 20 wherein the controlled shut-off valve
is further fluidly coupled to an exhaust pump.
22. The apparatus of claim 1 wherein the exhaust system further
comprises at least one trap for by-products of processing performed
in the process chamber, said traps are disposed upstream of the at
least one exhaust pump.
23. The apparatus of claim 20 wherein the at least one controlled
shut-off valve is open during dosing of the at least one process
gas and is closed during dosing of the at least one other process
gas.
24. The apparatus of claim 23 wherein the at least one controlled
shut-off valve opens and closes with a delay corresponding to a
travel time for the process gas in the path from the intake port
for the gas to the exhaust system.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of U.S. provisional patent
application serial No. 60/351,561, filed Jan. 25, 2002, which is
herein incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention generally relates to semiconductor
processing. More particularly, the invention relates to an
apparatus for performing cyclical deposition processes in
semiconductor substrate processing systems.
[0004] 2. Description of the Related Art
[0005] An atomic layer deposition (ALD) process is a cyclical
deposition method that is generally used for depositing ultra-thin
layers (e.g., mono-layers) over features of semiconductor devices
having a high aspect ratio, i.e., a ratio of the depth of a feature
to the smallest width of the feature.
[0006] The ALD process utilizes a chemisorption phenomenon to
deposit mono-layers of reactive precursor molecules. During the ALD
process, reactive precursors are injected, in the form of pulsed
gases, into a deposition chamber in a predetermined cyclical order.
Each injection of a precursor provides a new atomic layer on a
substrate that is additive to or combines with the previously
deposited layers. Injections of individual precursor gases
generally are separated by injections of a purge gas or, in other
embodiments, the purge gas may be flown continuously into the
deposition chamber. The purge gas generally comprises an inert gas,
such as argon (Ar), helium (He), and the like or a mixture thereof.
During the ALD process, the deposition chamber is also continuously
evacuated to reduce the gas phase reactions between the
precursors.
[0007] There are many challenges associated with ALD technique that
affect the film properties and costs of operation and ownership.
For example, unwanted gas phase reactions between precursors within
the process chamber of the prior art may cause contamination of
deposited films and require frequent cleaning of the chamber, thus
decreasing productivity of the ALD process.
[0008] Therefore, there is a need in an improved apparatus for
performing cyclical deposition of thin films during fabrication of
semiconductor devices.
SUMMARY OF THE INVENTION
[0009] The present invention is an apparatus for performing
cyclical deposition thin films on semiconductor substrates with low
film contamination and minimal gas phase reactions between the
precursors. The apparatus comprises a process chamber having a gas
distribution system facilitating separate paths for process gases
and an exhaust system that is synchronized with the valves dosing
the process gases. Various embodiments of the apparatus are
described. In one application, the invention is used to deposit an
aluminum oxide (Al.sub.2O.sub.3) film.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The teachings of the present invention can be readily
understood by considering the following detailed description in
conjunction with the accompanying drawings, in which:
[0011] FIG. 1 is a schematic, perspective view of one illustrative
embodiment of a semiconductor substrate processing system in
accordance with the present invention;
[0012] FIG. 2 is a schematic, cross-sectional view of a process
chamber of the processing system of FIG. 1;
[0013] FIG. 3 is a schematic, partial cross-sectional view of a lid
assembly of the process chamber of FIG. 2;
[0014] FIG. 4 is a schematic, partial view of a showerhead of the
process chamber of FIG. 2;
[0015] FIG. 5 is a schematic, partial cross-sectional view of
another embodiment of the lid assembly of the process chamber of
FIG. 2;
[0016] FIG. 6 is a schematic, partial cross-sectional view of
another embodiment of the process chamber of the processing system
FIG. 1;
[0017] FIG. 7 is a schematic, partial cross-sectional view of yet
another illustrative embodiment of the process chamber of the
processing system FIG. 1;
[0018] FIG. 8 is a schematic, partial cross-sectional view of one
embodiment of a showerhead of the process chamber of FIG. 7;
[0019] FIG. 9 is a schematic, partial cross-sectional view of
another embodiment of the showerhead of the process chamber of FIG.
7; and
[0020] FIG. 10 is a schematic, plan view of a processing platform
integrating the process chambers used in performing cyclical
deposition processes of the present invention.
[0021] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures.
[0022] It is to be noted, however, that the appended drawings
illustrate only exemplary embodiments of this invention and are
therefore not to be considered limiting of its scope, for the
invention may admit to other equally effective embodiments.
DETAILED DESCRIPTION OF THE INVENTION
[0023] The present invention is an apparatus for performing
cyclical deposition of thin films on semiconductor substrates
(e.g., using an atomic layer deposition (ALD) process and the like)
with low film contamination and minimal gas phase reactions between
the reactive precursors. In one application, the apparatus is used
to deposit an aluminum oxide (Al.sub.2O.sub.3) film. In other
applications, the apparatus may be used to deposit other films that
include materials such as aluminum (Al), copper (Cu), titanium
(Ti), tantalum (Ta), tungsten (W) films, hafnium (Hf), various
magnetic materials and the like.
[0024] FIGS. 1-9 are schematic views of various embodiments of an
exemplary processing system 100 and salient portions of the system
in accordance with the present invention. The images in FIGS. 1-9
are simplified for illustrative purposes and are not depicted to
scale.
[0025] FIG. 1 is a schematic, perspective view of one illustrative
embodiment of a processing system 100 comprising a process chamber
101, a controller 70, a dual exhaust system 50, and a source 530 of
process gases that are used during a cyclical deposition process
(e.g., ALD process).
[0026] The process chamber 101 comprises a chamber body 105, a lid
assembly 120, and an ozonator 170. In the depicted embodiment, the
process chamber 101 has two isolated zones (flow paths) for gaseous
compounds that are used during an ALD process. Herein the term
"gaseous compound" is collectively used for one or more process
gases, such as precursor gases, purge gases, carrier gases,
catalytic gases, and the like, as well as for mixtures thereof, and
the terms "gas" and "gas mixture" are used interchangeably. The
isolated flow paths prevent mixing of gaseous compounds before the
compounds reach a reaction region 159 of the process chamber 101.
In other embodiments, the process chamber 101 may comprise more
than two isolated flow paths.
[0027] The lid assembly 120 is disposed on the chamber body 105
and, in a closed position, forms a fluid-tight seal with the
chamber body. The lid assembly 120 generally comprises a lid plate
122, a ring heater 125, a manifold block 150, a showerhead 130, and
high-speed valves 155A, 155B. Components of the lid assembly 120
are preferably formed from process-compatible materials, such as
aluminum, aluminum nitride, stainless steel, graphite, silicon
carbide, and the like. The lid assembly 120 further comprises a
handle 145 and a hinge assembly 140 used to lift the lid assembly
during routine cleaning and maintenance of the process chamber
101.
[0028] The chamber body 105 comprises a member 109, a liner 107,
and a support pedestal 111. A slit 115 is formed in a sidewall of
the chamber body 105 to facilitate transfer of a substrate into and
out of the process chamber 101. One example of a suitable wafer
transfer robot (e.g., robot 1030 described in reference to FIG. 10)
is disclosed in commonly assigned U.S. Pat. No. 4,951,601.
[0029] The support pedestal 111, e.g., a ceramic support pedestal,
comprises a heater 53A, as well as a thermocouple 50A that is used
to monitor the temperature thereof. A signal from the thermocouple
50A may be used in a feedback loop that controls power applied to a
heater 53A. The heater 53A may be a resistive heater or other
thermal transfer device embedded in or otherwise coupled to the
support pedestal 111. Optionally, the support pedestal 111 may be
heated using a conduit (not shown) carrying a heat transfer fluid.
The support pedestal 111 may also comprise channels (not shown) to
deliver a purge gas to an edge and/or backside of the substrate.
Further, the substrate support 111 is coupled to a lifting
mechanism and comprises a chucking device that holds the substrate
thereon (both not shown). Examples of suitable chucking devices
include a vacuum chuck, an electrostatic chuck, a clamp ring, and
the like. One example of the lifting mechanism is described in the
commonly assigned U.S. Pat. No. 5,951,776.
[0030] The liner 107 circumscribes the interior vertical surfaces
of the chamber body 105. Alternatively, the liner 107 covers a
bottom of the chamber body 105 (as depicted in FIG. 2) or a
separate liner may be used to cover the bottom. The liner 107 may
be constructed of any process-compatible material. A purge channel
119 is formed between the liner 107 and the chamber body 105. The
purge gas is flown through the purge channel 119 to confine the
gaseous compounds within the reaction region 159, as well as to
minimize unwanted deposition on sidewalls of the chamber and
improve heat exchange between the sidewalls and the liner 107.
[0031] The member 109 defines gas conductance of a path to the
exhaust ports 117A, 117B. In one embodiment, the member 109 is an
annular ring having a plurality of apertures 109A. The apertures
109A facilitate uniform removal of gaseous compounds and
by-products out of the process chamber 101. A diameter, number, and
location of the apertures 109A may be determined based on
requirements of a particular ALD process. However, in some
embodiments, the member 109 may be omitted and, as such, is
considered optional.
[0032] The ring heater 125 is attached to the lid plate 120 using,
e.g., conventional fasteners, such as screws and the like.
Generally, the ring heater 125 comprises at least one embedded
electrical heating element (not shown). During the ALD process, the
ring heater 125 defines the temperature (e.g., about 90 degrees
Celsius or higher) of the lid plate 122 to prevent deposition of
gaseous compounds and by-products of the process on the lid
plate.
[0033] The high-speed valves 155A, 155B (e.g., electronically
controlled valves) are mounted on the manifold block 150 such that
a fluid-tight seal is provided between the manifold and a valve.
The seal may be provided using, e.g., a gasket (not shown) that is
placed between the upper surface of the manifold block 150 and
bottom surface of a high-speed valve and compressed thereafter.
Such gasket may be formed from stainless steel or other
compressible and process-compatible material. In one embodiment,
the manifold block 150 comprises one or more cooling channels (not
shown) disposed therein to protect the high-speed valves 155A, 155B
from exposure to excessive operating temperatures during the ALD
process. Generally, the manifold block 150 uses running water as a
heat transfer medium.
[0034] In operation, the high-speed valves 155A, 155B repeatedly
deliver, in a predetermined order, pulses of gaseous compounds into
the process chamber 101. The on/off periods of the valves are about
100 msec or less. The high-speed valves 155A, 155B are controlled
by the controller 70 or, alternatively, by an application specific
controller (nor shown), such as, e.g., described in commonly
assigned U.S. patent application serial No. 09/800,881, filed on
Mar. 7, 2001, which is incorporated herein by reference.
[0035] In one embodiment, the high-speed valves 155A, 155B are
three-port valves each having two intake ports and one outlet port.
In other embodiments, the process chamber 101 may also comprise
more than two high-speed valves. However, in other embodiments, a
high-speed valve may have only one intake port or more then two
ports. Suitable high-speed valves are available from Fujikin Inc.
of Japan and other suppliers.
[0036] In one exemplary application, one intake port of the valve
is coupled to a source a precursor gas, while the other intake port
is coupled to a source of a purge gas and the outlet port is
coupled to a respective outlet channel (channels 154A, 154B). More
specifically, one valve (e.g., valve 155A) doses a precursor gas
(e.g., aluminum precursor), the other valve (e.g., valve 155B)
doses an oxidizing gas (e.g., ozone), and the purge gas can
continuously flow through both valves.
[0037] FIG. 3 depicts isolated flow paths for individual gaseous
compounds. The paths are formed in the lid assembly 120 to separate
the compounds within the lid assembly. Generally, each gaseous
compound has a dedicated flow path, or, alternatively, the flow
path may deliver more than one compound, e.g., one precursor or
oxidizing gas and one purge gas. For simplicity of description,
embodiments of the invention are further described in terms of a
three gaseous compound processing system 100 using e.g., one
precursor gas, one oxidizing gas, and one purge gas. Such
processing system comprises at least two isolated flow paths.
However, in other embodiments, the processing system 100 may
comprise a different number of isolated flow paths and/or use a
different number of gaseous compounds.
[0038] The first flow path comprises an inlet channel 153A for a
fist gaseous compound (e.g., aluminum precursor, such as at least
one of trimethylaluminum (Al(CH3)3), triisopropoxyaluminum
(Al(C3H7)3), and dimethylaluminumhydride (Al(CH3)2H), as well as
precursors having a chemical structure Al(R1)(R2)(R3), where R1,
R2, R3 may be the same or different ligands, and the like), an
inlet channel 124A for a purge gas (e.g., helium (He), argon (Ar),
nitrogen (N2), hydrogen (H2), and the like), the high-speed valve
155A, and an outlet channel 154A. Similarly, the second flow path
comprises an inlet channel 153B for a second gaseous compound
(e.g., oxidizing gas, such as, e.g., ozone (O3), oxygen (O2), water
(H2O) vapor, nitrous oxide (N2O), nitric oxide (NO), and the like),
an inlet channel 124B for the purge gas, the high-speed valve 155B,
and an outlet channel 154B. The inlet channels 153A, 153B are
generally each coupled at a first end thereof to a source (not
shown) of an individual gaseous compound, as well as coupled at a
second end thereof to the respective valve 155A, 155B. The inlet
channels 124A, 124B similarly transfer one or more purge gases to
the valves 155A, 155B. In one embodiment, a diameter of the gas
channel 154A increases towards the showerhead 130 to decrease the
kinetic energy of the flowing gaseous compound.
[0039] In operation, in the depicted embodiment, the first gaseous
compound is dosed (pulsed) using the high-speed valve 155A and then
directed to the reaction region 159 through the outlet channel 154A
(in the manifold block 150 and lid plate 122) and centrally located
slotted openings 131A, 131B (discussed in reference to FIG.4) in
the showerhead 130. Similarly, the second gaseous compound is
pulsed using the high-speed valve 155B and then directed to the
reaction region 159 through the outlet channel 154B (in the
manifold block 150 and lid plate 122), a sealed cavity 156, and a
plurality of apertures 133 in the showerhead 130. As such, the
first and second gaseous compounds are separated from one another
within the lid assembly 120. The cavity 156 can be sealed using,
e.g., o-ring seals 139A, 139M that are disposed in the channels
129A, 129B, respectively.
[0040] A dispersion plate 132 is disposed near the slotted openings
131A, 131B and deflects, both horizontally and vertically, a flow
of the gaseous compound from the slotted openings 131A, 131B. The
plate converts a substantially vertical flow of the compound into
the partially horizontal flow and prevents the gaseous compound
from impinging directly on the substrate. The dispersion plate 132
may be a part of the showerhead 130 or, alternatively, may be
affixed to the showerhead. The dispersion plate 132 re-directs and
decreases velocity of the gaseous compound. Without such
re-direction, the impinging compound may sweep away (sputter)
reactive molecules already disposed on the substrate. Further, the
dispersion plate 132 prevents excess deposition onto regions of the
substrate that oppose the openings 131 A, 131 B and, as such,
facilitates uniform depositing of the film on the substrate.
[0041] FIG. 4 is a schematic, partial view of a portion of the
showerhead 130 taken along an arrow 157 in FIG. 3. In one
embodiment, the showerhead 130 comprises a plurality of apertures
133 disposed around the slotted openings 131A, 131B. In a further
embodiment, the apertures 133 comprise nozzles 130A to provide a
directional delivery of a gaseous compound to the substrate below.
In one embodiment, the nozzles 130A are angled relative to the
upper surface of the support pedestal 111. The apertures 133 and
nozzles 130A are sized and positioned to provide uniform
distribution of the gaseous compound across the substrate. In one
embodiment, the apertures 133 are formed on the entire surface of
the showerhead 130. In an alternative embodiment, the apertures 133
are formed substantially within a region opposing the support
pedestal 111. Although the openings 131A, 131B are shown having a
generally circular form factor, the openings may have any other
form factor that provides a desired pattern of a flow of a gaseous
compound in the reaction region 159. Further, in other embodiments,
a number of the centrally located openings in the showerhead 130
may be either one or greater than two.
[0042] The dual exhaust system 50 comprises an exhaust channel 108
formed in the liner 107, exhaust ports 117A, 117B) formed in a
sidewall of the process chamber 101, exhaust pumps 52A, 52B, and
valves 55A, 55B (e.g., electronic, pneumatic or ball valves and the
like). In one embodiment, operation of the valves 55A, 55B is
synchronized with operation of the high-speed valves 155A, 155B,
e.g., the valves 55A, 55B open and close contemporaneously with
such actions of the high-speed valves. During the ALD process, each
exhaust pump can be operated independently, and, preferably, is
used to remove specific gaseous compounds. In one illustrative
embodiment, one pump is used to remove an aluminum precursor and
the other pump is used to remove an oxidizing gas, while both pumps
are use simultaneously to remove the purge gas.
[0043] In this embodiment, a gaseous compound dosed into the
chamber body 150 using the high-speed valve 155A is exhausted from
the process chamber 101 through the exhaust valve 55A that is open
when the exhaust valve 55B is closed. Similarly, the gaseous
compound dosed into the process chamber 101 using the high-speed
valve 155B is exhausted from the chamber through the exhaust valve
55B that is open when the exhaust valve 55A is closed. As such, the
dual exhaust system 50 reduces mixing of gaseous compounds in the
processing system 100. Consequently, half reactions occur without
chemical combination that results in chemical vapor deposition
(CVD). By avoiding CVD, the chamber components and exhaust conduits
remain substantially free of deposited contaminants.
[0044] In a further embodiment, an off-cycle valve (i.e.,
temporarily closed valve) is not opened to the exhaust port
immediately upon initiation of a pulse of a gaseous compound, but
instead lags the pulse by a small time delay to reduce
cross-contamination of the gaseous compounds within the dual
exhaust system 50. Likewise, once both exhaust valves are open
during the purge step, the exhaust valve not associated with the
subsequent pulse of the other gaseous compound is closed just prior
to initiation of the pulse of the compound. Such synchronized
operation of the dual exhaust system 50 is generally performed by a
computer controller 70 or, alternatively, by the application
specific controller.
[0045] The dual exhaust system 50 may further comprise a trap (not
shown) disposed between the exhaust pump and exhaust valve or
between the chamber body 105 and exhaust valve. The trap removes
by-products of the ALD process from an exhaust stream thereby
increasing performance and service intervals of the exhaust pump.
The trap may be of any conventional type suited to collection of
by-products generated during the ALD process.
[0046] Although the dual exhaust system is described, in an
alternative embodiment, a single exhaust system may also be used.
Such exhaust system may utilize, e.g., the pump 52A (or 52B), the
optional trap, and the exhaust valve 55A (or 55B) coupled to the
exhaust port 117A (or 117B). In this embodiment, during an ALD
process, the exhaust pump is on and the exhaust valve is open.
[0047] The ozonator 170 (i.e., source of ozone) is in fluid
communication with a source of the precursor (e.g., oxygen), as
well as with inlet channels 124A, 124B in the manifold block 150.
Preferably, the ozonator 170 is disposed in close proximity to the
processing system 100 (as shown in FIG. 1), such that losses
associated with delivery of ozone into the process chamber 101 are
minimized. Ozonators are available, e.g., from ASTeX.RTM. Products
of Wilmington, Mass.
[0048] In another embodiment, the oxidizing gas may be produced
using, e.g., a remote source (not shown), such as a remote plasma
generator (e.g., DC, radio frequency (RF), microwave (MW) plasma
generator, and the like). The remote source produces reactive
species, which then are delivered to the process chamber 101. Such
remote sources are available from Advanced Energy Industries, Inc.
of Fort Collins, Colo. and others. Alternatively, the oxidizing gas
can be produced using a thermal gas break-down technique, a
high-intensity light source (e.g., UV or x-ray source), and the
like.
[0049] FIG. 5 is a schematic, partial cross-sectional view of an
alternative embodiment of the lid assembly 120 comprising the
ozonator 170 coupled to the process chamber 101 and to a buffer
cavity 520, through a diverter valve 510. Generally, the diverter
valve 510 couples the ozonator 170 to the process chamber 101
contemporaneously with an open state (with respect to the inlets
124A, 124B) of the high-speed valves 155A, 155B. Accordingly, the
diverter valve 510 couples the ozonator 170 to the buffer cavity
520 when the high-speed valves 155A, 155B are in close state in
respect to the inlets 124A, 124B. The buffer cavity 520 simulates a
second process chamber and, as such, using the diverter valve 510,
ozone and/or other oxidizing gas can be produced continuously
during the ALD process.
[0050] In one embodiment, the source 530 comprises an ampoule 531
containing a liquid aluminum precursor and a vaporizer 532. The
ampoule 531, the vaporizer 532, and delivering lines may each be
heated (e.g., using any conventional method of heating) to assist
in vaporization of the liquid phase, as well as in preventing the
vaporized precursor from condensing. Alternatively, the precursor
may be pre-mixed with a solvent that reduces viscosity of the
liquid phase, and then vaporized. A carrier gas, such as argon,
helium (He), hydrogen (H2), and the like may also be used to
facilitate delivery of the precursor, in a form of a gaseous
compound, to the process chamber 101.
[0051] FIG. 6 is a schematic, partial cross-sectional view of
another embodiment an ALD process chamber 301 comprising a
circumferential gas delivery assembly 300 and an upper gas delivery
assembly 350.
[0052] The circumferential gas delivery assembly 300 is disposed in
a chamber body 305 and comprises an annular gas ring 310 having at
least two separate gas distribution channels 316, 318 to supply at
least two separate gaseous compounds into the process chamber 301.
Each gas distribution channel is coupled to a source of a gaseous
compound and comprises a plurality of ports adapted for receiving
gas nozzles. As such, each gas distribution channel is in fluid
communication with a plurality of circumferentially mounted gas
nozzles. In one embodiment, alternating ports are connected to one
of the gas distribution channels, while the other ports are
connected to the other channel. In the depicted embodiment, a
gaseous compound from the source 352 is distributed through the
nozzles 302 of the gas distribution channel 316. Similarly, a
gaseous compound from the source 358 is distributed through the
nozzles 304 of the gas distribution channel 318.
[0053] The upper gas delivery assembly 350 is disposed in the lid
assembly 320 and comprises a center gas feed 312 and a nozzle 306.
Generally, the center gas feed 312 is in fluid communication with
two or more sources 364, 370 of other gaseous compounds.
[0054] Such embodiment provides, through the peripheral gas nozzles
302, 304 and the central gas nozzle 306, three separate passes for
the gaseous compounds (e.g., metal-containing precursor, oxidizing
gas, and inert gas) in the process chamber 301. Further, different
gaseous compounds can be introduced into a reaction volume at
select locations within the chamber. In the depicted embodiment,
the gaseous compounds are dosed using four high-speed valves
354A-354D each having one intake port and one outlet port. In other
embodiments, during a cyclical deposition process, at least one of
the gaseous compounds may be flown into the process chamber 101
continuously. In further embodiments, the gas delivery assembly 300
may comprise more than one annular gas ring 310 or the ring may
have more than two gas distribution channels, as well as the upper
gas delivery assembly 350 may comprise more than one gas nozzle
306.
[0055] Generally, the gas distribution ring 310 and the nozzles
302, 304, and 306 are made of a process-compatible material (e.g.,
aluminum, stainless steel, and the like), as well as are supplied
with conventional process-compatible fluid-tight seals (not shown),
such as o-rings and the like. The seals isolate the gas
distribution channels 316, 318 from one another. In one embodiment,
the nozzles 302, 304, and 306 are threaded in -the respective ports
to provide fluid-tight couplings therein, as well as means
facilitating prompt replacement of the nozzles. A form factor of
the restricting orifice of a nozzle can be selected for desired
dispersion of gaseous compound within the chamber.
[0056] FIG. 7 is a schematic, cross-sectional view of still another
embodiment of a process chamber 700 for performing the cyclical
deposition processes. The process chamber 700 comprises a chamber
body 702 and gas distribution system 730.
[0057] The chamber body 702 houses a substrate support 712 that
supports a substrate 710 in the chamber 700. The substrate support
712 comprises an embedded heater element 722. A temperature sensor
726 (e.g., a thermocouple) is embedded in the substrate support 712
to monitor the temperature of the substrate support 712.
Alternatively, the substrate 710 may be heated using a source of
radiant heat (not shown), such as quartz lamps and the like.
Further, the chamber body 702 comprises an opening 708 in a
sidewall 704 providing access for a robot to deliver and retrieve
the substrate 710, as well as exhaust ports 717A, 717 B (only port
717A is shown) that are fluidly coupled to the dual exhaust system
50 (discussed in reference to FIG. 1 above).
[0058] The gas distribution system 730 generally comprises a
mounting plate 733, a showerhead 770, and a blocker plate 760 and
provides at least two separate paths for gaseous compounds into a
reaction region 728 between the showerhead 770 and the substrate
support 712. In the depicted embodiment, the gas distribution
system 730 also serves as a lid of the process chamber 700.
However, in other embodiments, the gas distribution system 730 may
be a portion of a lid assembly of the chamber 700. The mounting
plate 733 comprises a channel 737 and a channel 743, as well as a
plurality of channels 746 that are formed to control the
temperature of the gaseous compounds (e.g., by providing either a
cooling or heating fluid into the channels). Such control is used
to prevent decomposing or condensation of the compounds. Each of
the channels 737, 743 provides a separate path for a gaseous
compound within the gas distribution system 730.
[0059] FIG. 8 is a schematic, partial cross-sectional view of one
embodiment of the showerhead 770. The showerhead 770 comprises a
plate 772 that is coupled to a base 780. The plate 772 has a
plurality of openings 774, while the base 780 comprises a plurality
of columns 782 and a plurality of grooves 784. The columns 782 and
grooves 784 comprise openings 783 and 785, respectively. The plate
772 and base 780 are coupled such, that the openings 783 in the
base align with the openings 774 in the plate to form a path for a
first gaseous compound through the showerhead 770. The grooves 784
are in fluid communication with one another and, together,
facilitate a separate path for a second gaseous compound into the
reaction region 728 through the openings 785. In an alternative
embodiment (FIG. 9), the showerhead 771 comprises the plate 750
having the grooves 752 and columns 754, and a base 756 comprising a
plurality of openings 758 and 759. In either embodiment, contacting
surfaces of the plate and base may be brazed together to prevent
mixing of the gaseous compounds within the showerhead.
[0060] Each of the channels 737 and 743 is coupled to a source (not
shown) of the respective gaseous compound. Further, the channel 743
directs the first gaseous compound into a volume 731, while the
channel 743 is coupled to a plenum 775 that provides a path for the
second gaseous compound to the grooves 784. The blocker plate 760
comprises a plurality of openings 762 that facilitate fluid
communication between the volume 731, plenum 729, and a plurality
of openings 774 that disperse the first gaseous compound into the
reaction region 728. As such, the gas distribution system 730
provides separate paths for the gaseous compounds delivered to the
channels 737 and 743.
[0061] In one embodiment, the blocker plate 760 and the showerhead
770 are electrically isolated from one another, the mounting plate
733, and chamber body 702 using insulators (not shown) formed of,
e.g., quartz, ceramic, and like. The insulators are generally
disposed between the contacting surfaces in annular peripheral
regions thereof to facilitate electrical biasing of these
components and, as such, enable plasma enhanced cyclical deposition
techniques, e.g., plasma enhanced ALD (PEALD) processing.
[0062] In one exemplary embodiment, a power source may be coupled,
e.g., through a matching network (both not shown), to the blocker
plate 760 when the showerhead 770 and chamber body 702 are coupled
to a ground terminal. The power source may be either a
radio-frequency (RF) or direct current (DC) power source that
energizes the gaseous compound in the plenum 729 to form a plasma.
Alternatively, the power source may be coupled to the showerhead
770 when the substrate support 712 and chamber body 702 are coupled
to the ground terminal. In this embodiment, the gaseous compounds
may be energized to form a plasma in the reaction region 728. As
such, the plasma may be selectively formed either between the
blocker plate 760 and showerhead 770, or between the showerhead 770
and substrate support 712. Such electrical biasing schemes are
disclosed in commonly assigned U.S. patent application Ser. No.
______, filed ______, (Attorney docket number 7660), which is
incorporated herein by reference.
[0063] In still another embodiment, the blocker plate 760 and
showerhead 770 may be coupled to separate outputs of the matching
network to produce an electrical field gradient to direct the
plasma species through the openings in the showerhead 770 towards
the substrate 710. In yet another alternative embodiment, to
produce the electrical field gradient, the blocker plate 760 and
showerhead 770 may be individually coupled to separate power
sources each using a separate matching network.
[0064] Referring to FIG. 1, the controller 70 comprises a central
processing unit (CPU) 123, a memory 116, and a support circuit 114.
The CPU 123 may be of any form of a general-purpose computer
processor that is used in an industrial setting. The software
routines can be stored in the memory 116, such as random access
memory, read only memory, floppy or hard disk drive, or other form
of digital storage. The support circuit 114 is coupled to the CPU
123 in a conventional manner and may comprise cache, clock
circuits, input/output sub-systems, power supplies, and the like.
The software routines, when executed by the CPU 123, transform the
CPU into a specific purpose computer (controller) 70 that controls
the reactor 100 such that the processes are performed in accordance
with the present invention. The software routines may also be
stored and/or executed by a second controller (not shown) that is
located remotely from the reactor 100.
[0065] FIG. 10 is a schematic, top plan view of an exemplary
integrated processing system 900 configured to form a film stack
having an aluminum oxide layer. One such integrated processing
system is a Centura.RTM. system that is available from Applied
Materials, Inc. of Santa Clara, Calif. The particular embodiment of
the system 900 is provided to illustrate the invention and should
not be used to limit the scope of the invention.
[0066] The system 1000 generally includes load lock chambers 1022
that protect vaccumed interior of the system 1000 from
contaminants. A robot 1030 having a blade 1034 is used to transfer
the substrates between the load lock chambers 1022 and process
chambers 1010, 1012,1014,1016, 1020. One or more of the chambers is
an aluminum oxide chamber, such as the process chambers described
above in reference to FIGS. 1-9. Further, one or more chambers may
be adapted to deposit a material used during fabrication of
integrated circuits, as well as be a cleaning chamber (e.g., a
plasma cleaning chamber) used to remove unwanted products from a
substrate. Example of such cleaning chamber is the Preclean IITM
chamber available from Applied Materials, Inc. of Santa Clara,
Calif. Optionally, one or more of the chambers 1010, 1012, 1014,
1016, 1020 may be an annealing chamber or other thermal processing
chamber, e.g., the RadianceTM chamber available from Applied
Materials, Inc. of Santa Clara, Calif. Further, the system 1000 may
comprise one or more metrology chambers 1018 connected thereto
using, e.g., a factory interface 1024. Alternatively, the system
1000 may comprise other types of process chambers.
[0067] One example of a possible configuration of the integrated
processing system 1000 includes a load lock chamber (chamber 1022),
an aluminum oxide cyclical deposition chamber (chamber 1010), a
first dielectric deposition chamber (chamber 1014), a metal
deposition chamber (chamber 1014), a second dielectric deposition
chamber (chamber 1016), and an annealing chamber (chamber
1020).
[0068] The processing system 100 may be used to deposit with low
film contamination and minimal gas phase reactions between the
precursors various metal-containing films, e.g., aluminum oxide,
copper, titanium, tantalum, tungsten films, and the like. In one
illustrative application, the processing system 100 is used to
deposit an aluminum oxide film. Various cyclical deposition
processes used to deposit the aluminum oxide and other films using
the processing system 100 are described in commonly assigned U.S.
provisional patent application serial No. 60/357,382, filed Feb.
15, 2002, which is incorporated herein by reference.
[0069] Although the forgoing discussion referred to the apparatus
for performing cyclical deposition processes, other processing
apparatuses can benefit from the invention. The invention can be
practiced in other semiconductor processing systems wherein the
parameters may be adjusted to achieve acceptable characteristics by
those skilled in the art by utilizing the teachings disclosed
herein without departing from the spirit of the invention.
[0070] While foregoing is directed to the illustrative embodiment
of the present invention, other and further embodiments of the
invention may be devised without departing from the basic scope
thereof, and the scope thereof is determined by the claims that
follow.
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